Hydrogen adsorption and diffusion through two dimensional aluminium : A first-principles investigation

With the exponentially growing global energy demand, green and clean renewable energy has become the need of the hour. To address the impending energy crisis, hydrogen has been proposed as an efficient and sustainable renewable energy source that has potential to replace conventional sources such as fossil fuels. Owing to their large surface-to-volume ratio and unique physiochemical properties, two-dimensional (2D) materials have been more recently explored for their energy storage potential. In this study, we investigate the adsorption of hydrogen molecule on a two-dimensional, free-standing aluminum monolayer using first-principles density functional theory calculations. We examine adsorption at four high symmetry sites in the honeycomb lattice: T (directly above the Al atom on the surface), D (directly above the Al atom in the buckled layer), H (hollow site at the center of the honeycomb lattice), and X (midway between Al bonds). The movement of hydrogen molecule during diffusion through the honeycomb hollow ring center of the aluminum monolayer is also studied using the Nudged Elastic Band (NEB) approach.